Higher bit depths are always going to mean more memory churn.
I’m guessing you have a working OpenCL stack, but it’s the software one, that is, OpenCL works, but the target is the CPU rather than the GPU. Check out your processor usage whilst doing the CL version, using ‘htop’ on the command line for example.
Try the ‘clinfo’ command, see what you get. Does it show your graphics card?
Also the 8 core Ryzen 7 doesn’t generally include a GPU does it? Which graphics card are you using?